An ingenious electrochemical system based on naphthalenediimide derivatives for ultrasensitive immunosensing of alpha-fetoprotein

It is crucial to develop highly efficient electrochemistry systems for sensitive detection of tumour markers. In this work, naphthalenediimide derivatives with electrochemical application potential were successfully synthesized and characterized. Electrochemistry and calculation of density functional theory (DFT) showed that 2,7-bis(4(dimethylamino)phenyl)benzo[lmn] [3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone (NDI-1) was an ideal candidate for electrochemical probe construction. Subsequently, based on the cyclic catalytic effect between NDI-1 and K2S2O8, a satisfying composite of GO/NDI-1/AuNPs was prepared and used to construct electrochemical probe for the design of ingenious sandwiched electrochemical immunosensor. Taking alpha-fetoprotein (AFP) as the model target biomarker, the designed immunosensor showed good detection performance for AFP, which exhibited wide range of linear response (10 fg/mL - 10 ng/mL), low detection limit (3.3 fg/mL). Moreover, the proposed immunosensor has been successfully applied to AFP detection in human serum, which provides the possibility for clinical applications. The designed electrochemical system provides a new electrochemical probe for the construction of immunosensors and may be extended to the electroanalysis of other biomolecules with recognition units.